Generally, wireless communication technologies have evolved for capacity improvement, cost reduction, and efficient use of resources.
Thus, in wireless communication, for improvement of capacity and efficient use of resources, various communication schemes have been proposed. For example, schemes for using resources such as time, frequency, code, and space are proposed communication schemes. That is, a Time Division Multiple Access (TDMA) scheme, a Frequency Division Multiple Access (FDMA) scheme, a Code Division Multiple Access (CDMA) scheme, and a Space Division Multiple Access (SDMA) scheme are proposed communication schemes.
In addition, as a communication scheme in a multi-antenna system using a beam, a Beam Division Multiple Access (BDMA) scheme has been proposed.
In the BDMA scheme, a transmitter of a multi-antenna system divides and uses beams by using a large number of antennas. The BDMA scheme is different from the SDMA scheme in a sense that the BDMA scheme allows communication through adaptive beam-forming without channel information. The BDMA scheme presumes that location information of a Base Station (BS) and location information of a Mobile Station (MS) are known. The BDMA scheme is a multiple access scheme using beam-forming and may be applied to a backhaul network between BSs and communication between a BS and an MS.
To obtain improved system capacity, a wireless communication system using the BDMA scheme (hereinafter, referred to as a “BDMA system”) considers a Multiple Input Multiple Output (MIMO) environment and analog beam designing. A representative example of such a BDMA system is a BDMA system having a two-stage beam-forming structure (hereinafter, referred to as a “hybrid beam-forming system”).
The two-stage beam-forming structure is used to collectively mean an analog-digital beam-forming structure. In another way, the two-stage beam-forming structure may be referred to as “hybrid analog/digital beam-forming”, “hybrid RF/baseband beam-forming”, or “hybrid beam-forming”. In the following description, for convenience of a description, the term “hybrid beam-forming” will be used.
However, the hybrid beam-forming system has a structure in which the number of antennas is greater than the number of digital chains. Thus, designing an analog beam considering channel information of all antennas is not realistic.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.